This paper investigates potential Stopping Sight Distance (SSD) violation on divided highways at left horizontal curves overlapped with crest vertical curves. The authors previously developed a SSD control methodology that relates the 3D configuration to the dynamics of a vehicle moving along the roadway. This methodology is applied for the assessment of critical design parameters related to both demanded and available SSD values. Initially, utilizing control geometric and driver – obstacle values adopted by AASHTO 2011 design policy, SSD inadequacy areas were revealed. Subsequently, on the basis of an explanatory modeling approach for a number of geometry parameters, evaluation of SSD sufficiency was carried out in terms of the probability of SSD inadequacy and the prediction of the object height in order to grant SSD adequacy (amended object height). These models may be useful to researchers and practitioners aiming to evaluate the interaction of the utilized design parameters in terms of SSD inadequacy.@en

An existing vehicle dynamics model was used to define design parameters up to which steady-state cornering conditions apply and consequently lift the restrictions of the point mass model. Besides a passenger car, the motion of a two-axle truck was examined as well for both loaded and unloaded conditions. In order to assess critical safety concerns in terms of vehicle skidding, a range of design speed values paired with control design elements from standard design guidelines as well as certain values of peak friction coefficients were used. The unloaded truck was found to be the most critical vehicle in terms of reaching a maximum constant speed, termed as safe speed. Furthermore, the authors provide modeling examples toward the development of a tool for practitioners to concurrently assess the impact of road geometry and friction in terms of defining the vehicle’s safe speed and, consequently, take certain actions. These actions include the adoption of acceptable arrangements for the above values, as well as scheduling accurate friction improvement programs.@en